Session recovery after network coordinator or AP restart for single user, multiple user, multiple access, and/or MIMO wireless communications

ABSTRACT

Session recovery after network coordinator or AP restart for single user, multiple user, multiple access, and/or MIMO wireless communications. Restart or reset of a network coordinator (e.g., an access point (AP) or other network coordinator type device) may occur for various reasons (e.g., a power cycle or power failure, inadequate failover protection, scheduled or planned power outages such as for including network maintenance, software upgrades, etc.). Upon determination of network coordinator restarted or reset, a singular bit within a communication from the network coordinator indicates synchronization or not of the its timing synchronization function (TSF) (e.g., with other devices in the communication system, such as wireless stations (STAs), smart meter stations (SMSTAs), etc.). A given device (e.g., STA, SMSTA, etc.) can provide its current TSF to the network coordinator so that it can resynchronize, re-establish its scheduled for wake times of those devices (e.g., target wake times (TWTs)), etc.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS ProvisionalPriority Claims

The present U.S. Utility Patent App. claims priority pursuant to 35U.S.C. §119(e) to the following U.S. Provisional Patent Apps. which arehereby incorporated herein by reference in their entirety and made partof the present U.S. Utility Patent App. for all purposes:

1 and 2. U.S. Provisional Patent App. Ser. No. 61/617,607 and61/776,725, both entitled “Session recovery after network coordinator orAP restart for single user, multiple user, multiple access, and/or MIMOwireless communications,” (Attorney Docket Nos. BP24611 and BP24611.1,respectively), filed Mar. 29, 2012 and Mar. 11, 2013, respectively, bothpending.

INCORPORATION BY REFERENCE

The following IEEE standards/draft standards are hereby incorporatedherein by reference in their entirety and are made part of the presentU.S. Utility Patent Application for all purposes:

1. IEEE Std 802.11™—2012, “IEEE Standard for Informationtechnology—Telecommunications and information exchange betweensystems—Local and metropolitan area Networks—Specific requirements; Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications,” IEEE Computer Society, Sponsored by the LAN/MANStandards Committee, IEEE Std 802.11™—2012, (Revision of IEEE Std802.11—2007), 2793 total pages (incl. pp. i-xcvi, 1-2695).

2. IEEE Std 802.11n™—2009, “IEEE Standard for Informationtechnology—Telecommunications and information exchange betweensystems—Local and metropolitan area Networks—Specific requirements; Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications; Amendment 5: Enhancements for Higher Throughput,” IEEEComputer Society, IEEE Std 802.11n™—2009, (Amendment to IEEE Std802.11™—2007 as amended by IEEE Std 802.11k™—2008, IEEE Std802.11r™—2008, IEEE Std 802.11y™—2008, and IEEE Std 802.11r™—2009), 536total pages (incl. pp. i-xxxii, 1-502).

3. IEEE P802.11ac™/D4.1, November 2012, “Draft STANDARD for InformationTechnology—Telecommunications and information exchange betweensystems—Local and metropolitan area networks—Specific requirements, Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)specifications, Amendment 4: Enhancements for Very High Throughput forOperation in Bands below 6 GHz,” Prepared by the 802.11 Working Group ofthe 802 Committee, 420 total pages (incl. pp. i-xxv, 1-395). 4. IEEEP802.11ad™/D9.0, July 2012, (Draft Amendment based on IEEE 802.11—2012)(Amendment to IEEE 802.11—2012 as amended by IEEE 802.11ae—2012 and IEEE802.11aa—2012), “IEEE P802.11ad™/D9.0 Draft Standard for InformationTechnology—Telecommunications and Information Exchange BetweenSystems—Local and Metropolitan Area Networks—Specific Requirements—Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications—Amendment 3: Enhancements for Very High Throughput in the60 GHz Band,” Sponsor: IEEE 802.11 Committee of the IEEE ComputerSociety, IEEE-SA Standards Board, 679 total pages.

5. IEEE Std 802.11ae™—2012, “IEEE Standard for Informationtechnology—Telecommunications and information exchange betweensystems—Local and metropolitan area Networks—Specific requirements; Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications,” “Amendment 1: Prioritization of Management Frames,”IEEE Computer Society, Sponsored by the LAN/MAN Standards Committee,IEEE Std 802.11ae™—2012, (Amendment to IEEE Std 802.11™—2012), 52 totalpages (incl. pp. i-xii, 1-38).

6. IEEE P802.11af™/D2.2, November 2012, (Amendment to IEEE Std802.11™—2012, as amended by IEEE Std 802.11ae™—2012, IEEE Std802.11aa™—2012, IEEE Std 802.11ad™/D9.0, and IEEE Std 802.11ac™/D4.0),“Draft Standard for Information Technology—Telecommunications andinformation exchange between systems—Local and metropolitan areanetworks—Specific requirements—Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications—Amendment 5: TVWhite Spaces Operation,” Prepared by the 802.11 Working Group of theIEEE 802 Committee, 324 total pages (incl. pp. i-xxiv, 1-300).

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates generally to communication systems; and, moreparticularly, it relates to session recovery after a restart of at leastone communication device within single user, multiple user, multipleaccess, and/or MIMO wireless communications.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11x,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

With various types of wireless communications (e.g.,single-output-single-input (SISO), multiple-input-single-output (MISO),single-input-multiple-output (SIMO), and multiple-input-multiple-output(MIMO)), it would be desirable to use one or more types of wirelesscommunications to enhance data throughput within a WLAN. For example,high data rates can be achieved with MIMO communications in comparisonto SISO communications. However, most WLAN include legacy wirelesscommunication devices (i.e., devices that are compliant with an olderversion of a wireless communication standard). As such, a transmittercapable of MIMO wireless communications should also be backwardcompatible with legacy devices to function in a majority of existingWLANs. Therefore, a need exists for a WLAN device that is capable ofhigh data throughput and is backward compatible with legacy devices.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication system.

FIG. 2 is a diagram illustrating an embodiment of a wirelesscommunication device.

FIG. 3 is a diagram illustrating an embodiment of an access point (AP)and multiple wireless local area network (WLAN) devices operatingaccording to one or more various aspects and/or embodiments of theinvention.

FIG. 4 is a diagram illustrating an embodiment of a wirelesscommunication device, and clusters, as may be employed for supportingcommunications with at least one additional wireless communicationdevice.

FIG. 5 illustrates an embodiment of OFDM (Orthogonal Frequency DivisionMultiplexing).

FIG. 6 illustrates an embodiment of a number of wireless communicationdevices implemented in various locations in an environment including abuilding or structure.

FIG. 7 illustrates an embodiment of a number of wireless communicationdevices implemented in various locations in a vehicular environment.

FIG. 8 illustrates an embodiment of a number of wireless communicationdevices implemented in various locations throughout a broadlydistributed industrial environment.

FIG. 9 illustrates an embodiment of restart detection of a communicationdevice.

FIG. 10 illustrates an alternative embodiment of restart detection of acommunication device.

FIG. 11 illustrates an embodiment of network coordinator (e.g., accesspoint (AP)) timing synchronization function (TSF) timer recovery.

FIG. 12 illustrates an embodiment of storing session encryption key.

FIG. 13 illustrates an embodiment of per association attributesrecovery.

FIG. 14 is a diagram illustrating an embodiment of a method foroperating one or more wireless communication devices.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication system 10 that includes a plurality of base stationsand/or access points 12-16, a plurality of wireless communicationdevices 18-32 and a network hardware component 34. The wirelesscommunication devices 18-32 may be laptop host computers 18 and 26,personal digital assistant hosts 20 and 30, personal computer hosts 24and 32 and/or cellular telephone hosts 22 and 28. The details of anembodiment of such wireless communication devices are described ingreater detail with reference to FIG. 2.

The base stations (BSs) or access points (APs) 12-16 are operablycoupled to the network hardware 34 via local area network connections36, 38 and 40. The network hardware 34, which may be a router, switch,bridge, modem, system controller, etc., provides a wide area networkconnection 42 for the communication system 10. Each of the base stationsor access points 12-16 has an associated antenna or antenna array tocommunicate with the wireless communication devices in its area.Typically, the wireless communication devices register with a particularbase station or access point 12-14 to receive services from thecommunication system 10. For direct connections (i.e., point-to-pointcommunications), wireless communication devices communicate directly viaan allocated channel.

Typically, base stations are used for cellular telephone systems (e.g.,advanced mobile phone services (AMPS), digital AMPS, global system formobile communications (GSM), code division multiple access (CDMA), localmulti-point distribution systems (LMDS), multi-channel-multi-pointdistribution systems (MMDS), Enhanced Data rates for GSM Evolution(EDGE), General Packet Radio Service (GPRS), high-speed downlink packetaccess (HSDPA), high-speed uplink packet access (HSUPA and/or variationsthereof) and like-type systems, while access points are used for in-homeor in-building wireless networks (e.g., IEEE 802.11, Bluetooth, ZigBee,any other type of radio frequency based network protocol and/orvariations thereof). Regardless of the particular type of communicationsystem, each wireless communication device includes a built-in radioand/or is coupled to a radio. Such wireless communication devices mayoperate in accordance with the various aspects of the invention aspresented herein to enhance performance, reduce costs, reduce size,and/or enhance broadband applications.

FIG. 2 is a diagram illustrating an embodiment of a wirelesscommunication device that includes the host device 18-32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component. For access points or base stations, thecomponents are typically housed in a single structure.

As illustrated, the host device 18-32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, etc. such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, etc. via the input interface 58 or generate the data itself.For data received via the input interface 58, the processing module 50may perform a corresponding host function on the data and/or route it tothe radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, a baseband processing module 64,memory 66, a plurality of radio frequency (RF) transmitters 68-72, atransmit/receive (T/R) module 74, a plurality of antennae 82-86, aplurality of RF receivers 76-80, and a local oscillation module 100. Thebaseband processing module 64, in combination with operationalinstructions stored in memory 66, execute digital receiver functions anddigital transmitter functions, respectively. The digital receiverfunctions include, but are not limited to, digital intermediatefrequency to baseband conversion, demodulation, constellation demapping,decoding, de-interleaving, fast Fourier transform, cyclic prefixremoval, space and time decoding, and/or descrambling. The digitaltransmitter functions, as will be described in greater detail withreference to later Figures, include, but are not limited to, scrambling,encoding, interleaving, constellation mapping, modulation, inverse fastFourier transform, cyclic prefix addition, space and time encoding,and/or digital baseband to IF conversion. The baseband processingmodules 64 may be implemented using one or more processing devices. Sucha processing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on operationalinstructions. The memory 66 may be a single memory device or a pluralityof memory devices. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, and/or any device that storesdigital information. Note that when the processing module 64 implementsone or more of its functions via a state machine, analog circuitry,digital circuitry, and/or logic circuitry, the memory storing thecorresponding operational instructions is embedded with the circuitrycomprising the state machine, analog circuitry, digital circuitry,and/or logic circuitry.

In operation, the radio 60 receives outbound data 88 from the hostdevice via the host interface 62. The baseband processing module 64receives the outbound data 88 and, based on a mode selection signal 102,produces one or more outbound symbol streams 90. The mode selectionsignal 102 will indicate a particular mode (e.g., such as may beidentified in corresponding mode selection table(s)), which appear atthe end of the detailed discussion. For example, the mode selectionsignal 102, may indicate a frequency band of 2.4 GHz or 5 GHz, a channelbandwidth of 20 or 22 MHz (e.g., channels of 20 or 22 MHz width) and amaximum bit rate of 54 megabits-per-second. In other embodiments, thechannel bandwidth may extend up to 1.28 GHz or wider with supportedmaximum bit rates extending to 1 gigabit-per-second or greater. In thisgeneral category, the mode selection signal will further indicate aparticular rate ranging from 1 megabit-per-second to 54megabits-per-second. In addition, the mode selection signal willindicate a particular type of modulation, which includes, but is notlimited to, Barker Code Modulation, BPSK, QPSK, CCK, 16 QAM and/or 64QAM. As may also be understood, a code rate is supplied as well asnumber of coded bits per subcarrier (NBPSC), coded bits per OFDM symbol(NCBPS), data bits per OFDM symbol (NDBPS).

The mode selection signal may also indicate a particular channelizationfor the corresponding mode. It is of course noted that other types ofchannels, having different bandwidths, may be employed in otherembodiments without departing from the scope and spirit of theinvention. For example, various other channels such as those having 80MHz, 120 MHz, and/or 160 MHz of bandwidth may alternatively be employedsuch as in accordance with IEEE Task Group ac (TGac VHTL6).

The baseband processing module 64, based on the mode selection signal102 produces the one or more outbound symbol streams 90 from the outputdata 88. For example, if the mode selection signal 102 indicates that asingle transmit antenna is being utilized for the particular mode thathas been selected, the baseband processing module 64 will produce asingle outbound symbol stream 90. Alternatively, if the mode selectsignal indicates 2, 3 or 4 antennae, the baseband processing module 64will produce 2, 3 or 4 outbound symbol streams 90 corresponding to thenumber of antennae from the output data 88.

Depending on the number of outbound streams 90 produced by the basebandmodule 64, a corresponding number of the RF transmitters 68-72 will beenabled to convert the outbound symbol streams 90 into outbound RFsignals 92. The transmit/receive module 74 receives the outbound RFsignals 92 and provides each outbound RF signal to a correspondingantenna 82-86.

When the radio 60 is in the receive mode, the transmit/receive module 74receives one or more inbound RF signals via the antennae 82-86. The T/Rmodule 74 provides the inbound RF signals 94 to one or more RF receivers76-80. The RF receiver 76-80 converts the inbound RF signals 94 into acorresponding number of inbound symbol streams 96. The number of inboundsymbol streams 96 will correspond to the particular mode in which thedata was received (recall that the mode may be any modes indicated inmode selection table(s)). The baseband processing module 64 receives theinbound symbol streams 96 and converts them into inbound data 98, whichis provided to the host device 18-32 via the host interface 62.

In one embodiment of radio 60 it includes a transmitter and a receiver.The transmitter may include a MAC module, a PLCP module, and a PMDmodule. The Medium Access Control (MAC) module, which may be implementedwith the processing module 64, is operably coupled to convert a MACService Data Unit (MSDU) into a MAC Protocol Data Unit (MPDU) inaccordance with a WLAN protocol. The Physical Layer ConvergenceProcedure (PLCP) Module, which may be implemented in the processingmodule 64, is operably coupled to convert the MPDU into a PLCP ProtocolData Unit (PPDU) in accordance with the WLAN protocol. The PhysicalMedium Dependent (PMD) module is operably coupled to convert the PPDUinto a plurality of radio frequency (RF) signals in accordance with oneof a plurality of operating modes of the WLAN protocol, wherein theplurality of operating modes includes multiple input and multiple outputcombinations.

An embodiment of the Physical Medium Dependent (PMD) module includes anerror protection module, a demultiplexing module, and a plurality ofdirection conversion modules. The error protection module, which may beimplemented in the processing module 64, is operably coupled torestructure a PPDU (PLCP (Physical Layer Convergence Procedure) ProtocolData Unit) to reduce transmission errors producing error protected data.The demultiplexing module is operably coupled to divide the errorprotected data into a plurality of error protected data streams Theplurality of direct conversion modules is operably coupled to convertthe plurality of error protected data streams into a plurality of radiofrequency (RF) signals.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 2 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the baseband processing module 64 and memory 66may be implemented on a second integrated circuit, and the remainingcomponents of the radio 60, less the antennae 82-86, may be implementedon a third integrated circuit. As an alternate example, the radio 60 maybe implemented on a single integrated circuit. As yet another example,the processing module 50 of the host device and the baseband processingmodule 64 may be a common processing device implemented on a singleintegrated circuit. Further, the memory 52 and memory 66 may beimplemented on a single integrated circuit and/or on the same integratedcircuit as the common processing modules of processing module 50 and thebaseband processing module 64.

FIG. 3 is a diagram illustrating an embodiment of an access point (AP)and multiple wireless local area network (WLAN) devices operatingaccording to one or more various aspects and/or embodiments of theinvention. The AP point 300 may compatible with any number ofcommunication protocols and/or standards, e.g., IEEE 802.11(a), IEEE802.11(b), IEEE 802.11(g), IEEE 802.11(n), as well as in accordance withvarious aspects of invention. According to certain aspects of thepresent invention, the AP supports backwards compatibility with priorversions of the IEEE 802.11x standards as well. According to otheraspects of the present invention, the AP 300 supports communicationswith the WLAN devices 302, 304, and 306 with channel bandwidths, MIMOdimensions, and at data throughput rates unsupported by the prior IEEE802.11x operating standards. For example, the access point 300 and WLANdevices 302, 304, and 306 may support channel bandwidths from those ofprior version devices and from 40 MHz to 1.28 GHz and above. The accesspoint 300 and WLAN devices 302, 304, and 306 support MIMO dimensions to4×4 and greater. With these characteristics, the access point 300 andWLAN devices 302, 304, and 306 may support data throughput rates to 1GHz and above.

The AP 300 supports simultaneous communications with more than one ofthe WLAN devices 302, 304, and 306. Simultaneous communications may beserviced via OFDM tone allocations (e.g., certain number of OFDM tonesin a given cluster), MIMO dimension multiplexing, or via othertechniques. With some simultaneous communications, the AP 300 mayallocate one or more of the multiple antennae thereof respectively tosupport communication with each WLAN device 302, 304, and 306, forexample.

Further, the AP 300 and WLAN devices 302, 304, and 306 are backwardscompatible with the IEEE 802.11 (a), (b), (g), and (n) operatingstandards. In supporting such backwards compatibility, these devicessupport signal formats and structures that are consistent with theseprior operating standards.

Generally, communications as described herein may be targeted forreception by a single receiver or for multiple individual receivers(e.g. via multi-user multiple input multiple output (MU-MIMO), and/orOFDMA transmissions, which are different than single transmissions witha multi-receiver address). For example, a single OFDMA transmission usesdifferent tones or sets of tones (e.g., clusters or channels) to senddistinct sets of information, each set of the sets of informationtransmitted to one or more receivers simultaneously in the time domain.Again, an OFDMA transmission sent to one user is equivalent to an OFDMtransmission (e.g., OFDM may be viewed as being a subset of OFDMA). Asingle MU-MIMO transmission may include spatially-diverse signals over acommon set of tones, each containing distinct information and eachtransmitted to one or more distinct receivers. Some single transmissionsmay be a combination of OFDMA and MU-MIMO. Multi-user (MU), as describedherein, may be viewed as being multiple users sharing at least onecluster (e.g., at least one channel within at least one band) at a sametime.

MIMO transceivers illustrated may include SISO, SIMO, and MISOtransceivers. The clusters employed for such communications (e.g., OFDMAcommunications) may be continuous (e.g., adjacent to one another) ordiscontinuous (e.g., separated by a guard interval of band gap).Transmissions on different OFDMA clusters may be simultaneous ornon-simultaneous. Such wireless communication devices as describedherein may be capable of supporting communications via a single clusteror any combination thereof. Legacy users and new version users (e.g.,TGac MU-MIMO, OFDMA, MU-MIMO/OFDMA, etc.) may share bandwidth at a giventime or they can be scheduled at different times for certainembodiments. Such a MU-MIMO/OFDMA transmitter (e.g., an AP or a STA) maytransmit packets to more than one receiving wireless communicationdevice (e.g., STA) on the same cluster (e.g., at least one channelwithin at least one band) in a single aggregated packet (such as beingtime multiplexed). In such an instance, channel training may be requiredfor all communication links to the respective receiving wirelesscommunication devices (e.g., STAs).

FIG. 4 is a diagram illustrating an embodiment of a wirelesscommunication device, and clusters, as may be employed for supportingcommunications with at least one additional wireless communicationdevice. Generally speaking, a cluster may be viewed as a depiction ofthe mapping of tones, such as for an OFDM symbol, within or among one ormore channels (e.g., sub-divided portions of the spectrum) that may besituated in one or more bands (e.g., portions of the spectrum separatedby relatively larger amounts). As an example, various channels of 20 MHzmay be situated within or centered around a 5 GHz band. The channelswithin any such band may be continuous (e.g., adjacent to one another)or discontinuous (e.g., separated by some guard interval or band gap).Oftentimes, one or more channels may be situated within a given band,and different bands need not necessarily have a same number of channelstherein. Again, a cluster may generally be understood as any combinationof one or more channels among one or more bands.

The wireless communication device of this diagram may be of any of thevarious types and/or equivalents described herein (e.g., AP, WLANdevice, or other wireless communication device including, though notlimited to, any of those depicted in FIG. 1, etc.). The wirelesscommunication device includes multiple antennae from which one or moresignals may be transmitted to one or more receiving wirelesscommunication devices and/or received from one or more other wirelesscommunication devices.

Such clusters may be used for transmissions of signals via various oneor more selected antennae. For example, different clusters are shown asbeing used to transmit signals respectively using different one or moreantennae.

Also, it is noted that, with respect to certain embodiments, generalnomenclature may be employed wherein a transmitting wirelesscommunication device (e.g., such as being an Access point (AP), or awireless station (STA) operating as an ‘AP’ with respect to other STAs)initiates communications, and/or operates as a network controller typeof wireless communication device, with respect to a number of other,receiving wireless communication devices (e.g., such as being STAs), andthe receiving wireless communication devices (e.g., such as being STAs)responding to and cooperating with the transmitting wirelesscommunication device in supporting such communications. Of course, whilethis general nomenclature of transmitting wireless communicationdevice(s) and receiving wireless communication device(s) may be employedto differentiate the operations as performed by such different wirelesscommunication devices within a communication system, all such wirelesscommunication devices within such a communication system may of coursesupport bi-directional communications to and from other wirelesscommunication devices within the communication system. In other words,the various types of transmitting wireless communication device(s) andreceiving wireless communication device(s) may all supportbi-directional communications to and from other wireless communicationdevices within the communication system. Generally speaking, suchcapability, functionality, operations, etc. as described herein may beapplied to any wireless communication device. Various aspects andprinciples, and their equivalents, of the invention as presented hereinmay be adapted for use in various standards, protocols, and/orrecommended practices (including those currently under development) suchas those in accordance with IEEE 802.11x (e.g., where x is a, b, g, n,ac, ad, ae, af, ah, etc.).

FIG. 5 illustrates an embodiment 500 of OFDM (Orthogonal FrequencyDivision Multiplexing). OFDM modulation may be viewed as dividing up anavailable spectrum into a plurality of narrowband sub-carriers (e.g.,lower data rate carriers). Typically, the frequency responses of thesesub-carriers are overlapping and orthogonal. Each sub-carrier may bemodulated using any of a variety of modulation coding techniques.

OFDM modulation operates by performing simultaneous transmission of alarger number of narrowband carriers (or multi-tones). Oftentimes aguard interval (GI) or guard space is also employed between the variousOFDM symbols to try to minimize the effects of ISI (Inter-SymbolInterference) that may be caused by the effects of multi-path within thecommunication system (which can be particularly of concern in wirelesscommunication systems). In addition, a CP (Cyclic Prefix) may also beemployed within the guard interval to allow switching time (when jumpingto a new band) and to help maintain orthogonality of the OFDM symbols.Generally speaking, OFDM system design is based on the expected delayspread within the communication system (e.g., the expected delay spreadof the communication channel).

In certain instances, various wireless communication devices may beimplemented to support communications associated with monitoring and/orsensing of any of a variety of different conditions, parameters, etc.and provide such information to another wireless communication device.For example, in some instances, a wireless communication device may beimplemented as a smart meter station (SMSTA), having certaincharacteristics similar to a wireless station (STA) such as in thecontext of a wireless local area network (WLAN), yet is operative toperform such communications associated with one or more measurements inaccordance with monitoring and/or sensing. In certain applications, suchdevices may operate only very rarely. For example, when compared to theperiods of time in which such a device is in power savings mode (e.g., asleep mode, a reduced functionality operational mode a lowered poweroperational mode, etc.), the operational periods of time may beminiscule in comparison (e.g., only a few percentage of the periods oftime in which the device is in such a power savings mode).

For example, such a device may awaken from such a power savings modeonly to perform certain operations. For example, such a device mayawaken from such a power savings mode to perform sensing and/ormeasurement of one or more parameters, conditions, constraints, etc.During such an operational period (e.g., in which the device is not in apower savings mode), the device may also perform transmission of suchinformation to another wireless communication device (e.g., an accesspoint (AP), another SMSTA, a wireless station (STA), or such an SMSTA orSTA operating as an AP, etc.). It is noted that such a device may enterinto an operational mode for performing sensing and/or monitoring at afrequency that is different than (e.g., greater than) the frequency atwhich the device enters into an operational mode for performingtransmissions. For example, such a device may awaken a certain number oftimes to make successive respective sensing and/or monitoringoperations, and such data as is acquired during those operations may bestored (e.g., in a memory storage component within the device), andduring a subsequent operational mode dedicated for transmission of thedata, multiple data portions corresponding to multiple respectivesensing and/or monitoring operations may be transmitted during thatoperational mode dedicated for transmission of the data.

Also, it is noted that, in certain embodiments, such a device mayinclude both monitor and/or sensor capability as well as wirelesscommunication capability. In other embodiments, such a device may beconnected and/or coupled to a monitor and/or sensor and serve toeffectuate wireless communications related to the monitoring and/orsensing operations of the monitor and/or sensor.

The application contexts of such devices may be very, and some exemplarythose non-exhaustive embodiments are provided in described below forillustrations the reader. It is also noted that, in some applications,some of the devices may be battery operated in which energy conservationand efficiency may be of high importance. In addition, there are anumber of applications in which such devices may be used besides inaccordance with smart meter applications; for example, certain wirelesscommunication devices may be implemented to support cellular offloadand/or other applications that are not normally or traditionallyassociated with WLAN applications. Some applications are particularlytargeted and directed towards use in accordance with and in compliancewith the currently developing IEEE 802.11ah standard.

It is noted that the in accordance with various aspects, and theirequivalents, of the invention described herein may be generally appliedto wireless communication devices including any number of types ofwireless communication devices (e.g., STAs, APs, SMSTAs, and/or anycombination thereof, etc.), certain desired embodiments are particularlytailored towards use with one or more SMSTAs.

FIG. 6 illustrates an embodiment 600 of a number of wirelesscommunication devices implemented in various locations in an environmentincluding a building or structure. In this diagram, multiple respectivewireless communication devices are implemented to forward informationrelated to monitoring and/or sensing to one particular wirelesscommunication device that may be operating as a manager, coordinator,etc. such as may be implemented by an access point (AP) or a wirelessstation (STA) operating as an AP. Generally speaking, such wirelesscommunication devices may be implemented to perform any of a number ofdata forwarding, monitoring and/or sensing operations. For example, inthe context of a building or structure, there may be a number ofservices that are provided to that building or structure, includingnatural gas service, electrical service, television service, Internetservice, etc. Alternatively, different respective monitors and/orsensors may be implemented throughout the environment to performmonitoring and/or sensing related to parameters not specifically relatedto services. As some examples, motion detection, temperature measurement(and/or other atmospheric and/or environmental measurements), etc. maybe performed by different respective monitors and/or sensors implementedin various locations and for various purposes.

Different respective monitors and/or sensors may be implemented toprovide information related to such monitoring and/or sensing functionswirelessly to the manager/coordinator wireless communication device.Such information may be provided continuously, sporadically,intermittently, etc. as may be desired in certain applications. Inaddition, such communications between such a manager/coordinatorwireless communication device of the different respective monitorsand/or sensors may be cooperative in accordance with such bidirectionalindications, in that, the manager/coordinator wireless communicationdevice may direct the respective monitors and/or sensors to performcertain related functions at subsequent times.

FIG. 7 illustrates an embodiment 700 of a number of wirelesscommunication devices implemented in various locations in a vehicularenvironment. This diagram pictorially depicts a number of differentsensors implemented throughout a vehicle which may perform any of anumber of monitoring and/or sensing functions. For example, operationalcharacteristics associated with different mechanical components (e.g.,temperature, operating condition, etc. of any of a number of componentswithin the vehicle, such as the engine, compressors, pumps, batteries,etc.) may all be monitored and information related to that monitoringmay be provided to a coordinator/manager wireless communication device.

FIG. 8 illustrates an embodiment 800 of a number of wirelesscommunication devices implemented in various locations throughout abroadly distributed industrial environment. This diagram pictoriallyillustrates a number of different respective sensors that may beimplemented in various locations are very remote with respect to oneanother. This diagram relates to a number of sensors was may beimplemented within different locations that have little or no wirelesscommunication infrastructure associated therewith. For example, in theoil industry, different respective pumps may be implemented in veryremote locations, and service personnel need physically to visit thedifferent respective locations to ascertain the operation of the variousequipment and components there. A manager/coordinator wirelesscommunication device may be implemented within a vehicle, or within aportable component such as laptop computer included within the vehicle,and as the vehicle travels to each respective location in which thereare such sensing and/or monitoring devices. As the manager/coordinatorwireless communication device enters within sufficient proximity suchthat wireless communication may be supported with the differentrespective sensing and/or monitoring devices, information related tosuch monitoring and/or sensing functions may be provided to themanager/ordinate wireless communication device.

While various respective and exemplary embodiments have been providedhere for illustration to the reader, it is noted that such applicationsare non-exhaustive and that any of a variety of application contexts maybe implemented such that one or more wireless communication devices areimplemented throughout an area such that those one or more wirelesscommunication devices may only occasionally provide information to amanager/ordinate wireless communication device. Any such application orcommunication system may operate in accordance with the in accordancewith various aspects, and their equivalents, of the invention.

Within various types of communication systems, including those which mayinclude one or more wireless communication devices that are awake,active, etc. only a relatively small portion or percentage of the time,a restart of a network coordinator (e.g., an access point (AP) or othernetwork coordinator type device) may occur for any of a number ofreasons. For example, a power cycle or power failure may result in sucha restart. In certain instances, a power failure may exceed the periodof time in which power may be provided via a battery backup, and ifthere is inadequate failover protection, such a device may undergo arestart. In addition, sometimes scheduled or planned power outages occurfor any of a number of reasons including network maintenance, softwareupgrades, etc.

For example, in the context of wireless communication systems operatingin accordance with the developing IEEE 802.11ah, certain embodimentsenvision a significant number of wireless stations (e.g., which mayinclude several thousand STAs, smart meter devices, etc.) incommunication with as few as one single network coordinator. Again, insome embodiments, there may be a wide range of operability of thevarious communication devices therein. For example, certain of thewireless communication devices may be in and inactive, reducedfunctionality, or sleep mode during a majority of the time such thatthey are infrequently operable devices (e.g., awaking only at certaintimes to effectuate transmission and/or receipt of one or more signals).In such application contexts, when such a network coordinator (e.g., AP)undergoes a restart, the network coordinator (e.g., AP) may loseassociation with a number of these respective wireless communicationdevices, lose timing synchronization function (TSF), lose association ID(AID) for the respective devices, lose the traffic indication map (TIM)associated with the respective devices, and/or lose session encryptionkeys associated with the respective devices. That is to say, therespective association attributes which were previously in use are nolonger valid after such a restart.

In addition, devices awakened from a relatively long period of sleep maybe unaware of such a restart of the network coordinator (e.g., AP). Assuch, certain of the devices may be required to repeat association,authentication, etc. to resume and effectuate communications within thecommunication system. In addition, an invalid TIM bitmap mayunfortunately mislead certain devices to operate in undesired ways. Forexample, after a reset, such a network coordinator (e.g., AP) may sendout new beacons, management frames, and/or other communications aftersuch a restart. However, if a particular device was asleep when suchinformation was sent out, then that device won't know about or beinformed of this new information (e.g., beacons, management frames,and/or other communications).

In accordance with operating after such a restart has occurred, certainsteps may typically be performed for association, authentication, etc.for a particular device to regain access to the communication network.For example, in association request and response exchange may occur.Also, device and/or user authentication may occur, and key generationand distribution may also occur. Such operational steps for a device tobe gain network access may take a relatively significant amount of time.In addition, depending upon the authentication mode being employed,multiple respective frame transactions lasting several seconds may beneeded (e.g., lasting approximately 2 to 3 seconds).

For example, considering a concrete example, authentication exchangeshave been measured at one particular Wi-Fi implementation required anassociated 28 frame exchanges between the respective wirelesscommunication devices (e.g. STAs) in the network coordinator (e.g., AP)lasting a relatively long period of time (e.g., approximate 2.78seconds). This was measured starting from start of an extensibleauthentication protocol (EAP) over local area network (LAN)(alternatively referred to as EAPOL-Start) to EAP-success.

Again, as mentioned elsewhere herein, certain embodiments of a basicservices set (BSS) operative in accordance with the developing IEEE802.11ah may include a significant large number of devices. Consideringembodiment including 6000 smart meter devices, and assuming that eachrespective device takes approximately 3 seconds on average forassociation authentication, then the time required to effectuateassociation on authentication for those respective devices would beapproximate 6000×3 seconds=12.5 days to reattach all of the respectivesmart meters to the BSS. Again, considering even a best case scenario ofsuch an embodiment including several thousand wireless devices (e.g.,6000 smart meters), almost two weeks would be necessitated to effectuatereattachment of all the respective smart meters to an AP in such a BSS.In addition, it is noted that such a consideration is not necessarilyaccounting for access delay, traffic from other non-smart meter devices,and/or extra power consumed associated with effectuating reattachment ofsuch devices within a BSS after a restart of the AP. A worst-casescenario could take significantly longer than two weeks to effectuatereattachment of all the respective smart meters.

As may be understood, a number of deleterious effects may occur basedupon the restart of a network coordinator (e.g., AP). There may be asignificant loss of throughput performance, unstable behavior from smartmeters with relatively short wake and long sleep times may occur, arelatively lengthy BSS recovery time may be exhibited (bounded by thelongest sleep time of the respective devices within the network), and/oran increase in power consumption may be effectuated at respective clientdevices within the network. In addition, after such a restart, basedupon AID reassignments, a given AID may unfortunately be reassigned to adifferent device. In certain instances two or more respective devicesmay have the same AID assigned thereto which could become problematic.

Generally speaking, such an appropriately designed approach for dealingwith such a restart should achieve high availability with a minimalamount of network management required. Herein, a number of differentembodiments and approaches are presented by which one or more devicesmay detect a restart of another device within the network (e.g., anetwork coordinator, AP, etc.). Also, recovery of a timingsynchronization function (TSF) timer may be made based on certain of thevarious embodiments and approaches presented. As may also be understood,certain aspects provided by such embodiments and approaches presentedherein allow for the avoidance of repeating association onauthentication for all of the devices within the system as well as allowfor restoration of association attributes at the network coordinator(e.g., AP) as well. In certain embodiments, such as those operating inaccordance with residential contexts, approximately 3 respective smartmeters may be implemented with respect to each respective home,apartment, etc. For example, three respective smart meters may beimplemented: a first smart meter associated with the electric powersystem, a second smart meter associated with a natural gas deliverysystem, and a third smart meter associated with a water delivery and/orsewer system, each respectively operative to effectuate certain purposessuch as revenue metering. Of course, different respective embodimentsmay include fewer or more respective smart meters associated with eachrespective home, apartment, etc. In addition, similar implementations ofsmart meters may be implemented with respect to commercial properties aswell without departing from the scope and spirit of the invention.

FIG. 9 illustrates an embodiment 900 of restart detection of acommunication device. As may be seen with respect to this diagram, onemanner by which a restart of a network coordinator (e.g., AP) sees maybe made is by assessing or monitoring the value of the TSF timer. Forexample, based upon the identification of a given or current TSF valuebeing less than a prior TSF value, such a restart may be detected. Sucha TSF timer may be viewed as being the common BSS clock that ismaintained at the network coordinator (e.g., AP), and such a TSF timermay be denoted by an 8 byte timestamp field. When such a networkcoordinator (e.g., AP) first boots up, the TSF timer begins countingstarting from zero (0). Such a TSF timer increases in incremental stepsof a particular duration (e.g., steps of 1 μs). The TSF timer wrapsaround in 585 millennia (that is, after 585,000 years) in consideringand 8 byte TSF timer. Also, such a network coordinator (e.g., AP) resetits respective TSF timer back to zero after every restart. A device maybe implemented to detect the restart of a network coordinator (e.g., AP)(at least once) of the received TSF timer as being relatively less thanthe next expected value. That is to say, the value of the TSF timershould be continually increasing in size until it wraps around afterapproximately 585,000 years. If a first TSF value is assessed, and thena second TSF value is assessed at a later time such that the second TSFvalue is relatively less than the first TSF value, then a restart of thenetwork coordinator (e.g., AP) may be detected. Considering a concreteexample, if the first time that a device associates with a networkcoordinator (e.g., AP), that device identifies the TSF value of 1000 andincreasing, and then during a second time that that same deviceassociates with a network coordinator (e.g., AP), that device identifiesthe TSF value as being 100 and increasing, then that particular devicemay detect that a restart of the network coordinator (e.g., AP) has infact occurred.

FIG. 10 illustrates an alternative embodiment 1000 of restart detectionof a communication device. Considering the very long time duration atwhich the TSF timer wraps around (e.g., proximally 585,000 years), onepossible embodiment operates by adding a new restart count field to thetimestamp and/or TSF. That is to say, a new field may be added to thetimestamp and/or TSF to indicate the number of network coordinator(e.g., AP) restarts that has occurred. Generally speaking, any desirednumber of bits or bytes may be allocated for such a network coordinator(e.g., AP) restart count. In one preferred embodiment, 1 out of 8 bytesof the timestamp and/or TSF is dedicated and employed for the networkcoordinator (e.g., AP) restart count. Considering even a 7 byte TSFtimer (e.g., considering employing 1 of the bytes for the networkcoordinator (e.g., AP) restart count), even such a modified 7 byte TSFtimer would wrap around only in approximately 2.28 millennia (that is,after 2280 years). In one possible embodiment, such a networkcoordinator (e.g., AP) restart count and/or TSF timer may be maintainedin a non-volatile random access memory (NVRAM) implemented within such anetwork coordinator (e.g., AP), so that even in the event of a hardpower failure, such information could subsequently be retrieved therefrom. Using such an approach, a given device can detect with greatspecificity the number of restarts performed by a network coordinator(e.g., AP) based on changes to the value in such a network coordinatorrestart (e.g., AP) count field.

With respect to network coordinator recovery indication, a networkcoordinator with associated devices restarts, and then loses BSSattributes. As described elsewhere herein, there are at least twoalternative ways by which a restart may be determined: by assessing theTSF value or a network coordinator restart count field within the TSFtimer.

In addition, one or more new fields or information elements (IE(s)) maybe included within beacons to indicate information that may need to beupdated from certain respective communication devices. For example, suchinformation may be included within beacons or in one or more newinformation elements. For example, a number of respective types ofinformation may need updating. The TSF itself may need updating, whichmay be BSS specific. In addition, an AID (which is device specific) mayoptionally be updated and/or reassigned. Also, a target weight time(TWT) (which is despite specific) may also optionally be updated and/orreassigned.

A given device may receive a beacon from a network coordinator with arecovery indication therein. Based on this recovery indication, thatdevice may send a recovery request action frame to the networkcoordinator. Based upon such an exchange, the network coordinator (e.g.,AP) may update the TSF timer for the BSS, and then send a recoveryresponse (e.g., such as an acknowledgment to the recovery request actionframe) to indicate the respective success or failure of the update ofthe TSF timer.

With respect to TSF timer recovery associated with a networkcoordinator, if such a network coordinator resets its TSF timer, thenthere may be some instances in which a great number of devices (e.g.,several thousand devices in a smart meter type application) fall out oftime synchronization. Consequently, most of these respective deviceswould then wake up at the incorrect time and miss the beacon (whichwould typically be transmitted at the target beacon transmit time(TBTT)). That is to say, if a given device wakes up based on a prior TSFtimer-based synchronization, then there is a high likelihood that asubsequent wake up of that same device, after a restart of the networkcoordinator in which the TSF timer associated there with his reset aswell, would not occur at the proper time. Consequently, in someembodiments, each respective device would either have to stay awake andwait until the next received beacon, or each respective device wouldneed to send a probe request to the network coordinator. However, again,considering an embodiment having a great number of devices (e.g.,several thousand devices), it may be understood that it may beinefficient or undesirable if every respective device within the systemoperates in accordance with this manner. Instead, rather than updatingthe TSF timers associated with all of the respective devices within thenetwork, the TSF timer associated with the network coordinator (e.g.,AP) could instead be updated with the current TSF timer which may beprovided from one of the devices within the system (e.g., provided fromthe next waking device within the system).

FIG. 11 illustrates an embodiment 1100 of network coordinator (e.g.,access point (AP)) timing synchronization function (TSF) timer recovery.It is noted here that general references to a network coordinator and/orAP may be used interchangeably without loss of generality. While it isnoted that an AP is a specific example of one type of networkcoordinator, embodiments and/or diagrams included herein employing an APtherein may alternatively be modified by generally employing a networkcoordinator therein without departing from the scope and spirit of theinvention.

As may be seen with respect to this diagram, after an AP effectuate arestart, the AP beacon associated there with would go out of timesynchronization. That is to say, the AP would not know exactly when youshould send out its beacon based upon the resetting of the TSF timertherein. However, after a given wireless device (STA2) awakens andmisses a beacon, then that given device could stay awake until the nextbeacon. Using any one of the approaches presented herein to determine oridentify an AP restart, the device may determine that the AP restartcount and/or the TSF is changed. Based upon such determination, thisgiven device could send an AP recovery request to the AP to update theTSF associated with the AP. In response, the AP could transmit an APrecovery response (e.g., an acknowledgment) back to that device that hasprovided the AP recovery request indicating the success or failure ofthe updating of the TSF timer within the AP. As may be understood, sucha given device (e.g., STA2) wakes up but does not receive the beacon atthe expected time, so that given device stays awake for a relativelylong time. When a beacon is eventually received from the AP, the APbeacon will indicate that (1) the AP has restarted (e.g., based onrestart count and will consequently have lost association informationrelated to the respective devices within the system) and also indicate(2) which information needs to be required from one or more of thedevices (e.g., STAs) within the system. As they be understood, suchoperations may effectuate getting the AP back to its original clock, sothat there is no need to perform resynchronization with all of the otherrespective devices within the system (which can number several thousandin certain embodiments). In such an implementation, only the AP needs toundergo resynchronization with its prior or original clock.

Consequently, another subsequent device (e.g., STA3) will awake at theappropriate time to receive a beacon from the AP, just as yet anotherdevice (e.g., STA1) appropriately awoke at the appropriate time toreceive a beacon from the AP prior to the AP restart. However, thisparticular device (e.g., STA3) will also determine that the AP restartcount has changed, and certain updating may occur in relation to one ormore device attributes with such an AP recovery.

FIG. 12 illustrates an embodiment 1200 of storing session encryptionkey. To avoid a repeat association and authentication operations to beperformed after every AP restart, such an AP may store certaininformation therein within NVRAM for each respective associated devicewithin the system. For example, the AP may store the session encryptionkey (Master Session Key) in NVRAM for each respective associated devicewithin the system. Such operation may obviate the need for uplink dataretransmission from decryption failures. The table depicted within thisdiagram shows an embodiment of possible sizes associated with differenttypes of decryption keys.

FIG. 13 illustrates an embodiment 1300 of per association attributesrecovery. As may be understood, a number of different respectiveattributes may be associated with the different respective deviceswithin a given system. To minimize the amount of information that wouldneed to be stored within an AP (e.g., such as within NVRAM therein), perdevice attributes at the AP can be restored from each respective device.For example, such association attributes may be related to any of anumber of parameters including target weight time (TWT), association ID(AID), and/or any other parameter, etc.

Each respective device may detect that the AP has lost state (e.g., lostper association attributes) based upon an AP restart count. In responseto such detection, a given device may send an AP recovery request asrequested through an AP recovery indication. Upon receipt of such anaction frame, an AP may either update one or more of the values of theseattributes or reassign new values associated with one or more of thesevalues and notify that particular device in the AP recovery responseframe (e.g., the acknowledgment).

In certain embodiments, the TSF alone is insufficient to indicate thatthe AP has in fact restarted or rebooted. For example, since the TSF mayhave been restored by an earlier device, certain embodiments maypreferentially use the AP restart count (e.g., such as described withreference to FIG. 10) to indicate any reboot or restart of the AP. Ofcourse, it is noted that different respective implementations may preferone manner of indicating AP restart or reboot over another.

As may be understood with respect to FIG. 13, recovery of perassociation attributes (e.g., using AID in this exemplary embodiment)may be made in accordance with the AP recovery request/response exchangebetween a given device in the AP. Again, it is noted that while recoveryof AID is described with reference to this diagram, any desired perassociation attribute may be analogously recovered using such anapproach. As may be seen with respect to the diagram, the AP undergoes arestart, and the AP then recovers the TSF timer from one of the deviceswithin the system (e.g., the next waking STA). In a subsequentlytransmitted beacon from the AP, and AP recovery indication is markedtherein (e.g., indicating AID in one particular embodiment). A givendevice wakes and successfully receives a beacon, determines that the APhas in fact restarted or rebooted, and therefore ignores its trafficindication map (TIM) bit. The AP has requested recovery of a particularattribute associated with the device (e.g., AID), and the given deviceis then prompted to send the AP recovery request with that particularattribute information therein (e.g., its current AID). In response tothe information of that particular attribute provided within the APrecovery request, the AP may then either respond by accepting theinformation included therein (e.g., accepting the current AID from theSTA) or by reassigning a new attribute for that particular device (e.g.,reassigning a new AID for that STA).

As may be understood with respect to the various diagrams, embodiments,etc. herein, the restart of a network coordinator (e.g., AP) can resultin performance loss and unreliable operation of other respective deviceswithin the system. Herein, a number of different approaches have beenpresented to detect whether or not an AP has restarted or rebooted aswell as a number of different approaches by which the per deviceassociation attributes may be restored with minimal downtime. Suchdetermination of AP restart/reboot and per device association attributerestoration may be achieved with relatively minimal network managementcosts.

As may be understood, various approaches are presented herein by which arestart or reset of a communication device (e.g., access point (AP)) maybe determined, including analyzing the signal provided or received fromsuch a communication device. For example, a processor in such acommunication device (e.g., wireless station (STA)) may operate todetermine that the other communication device has undergone the restartor reset when a timing synchronization function (TSF) value within thefirst signal is different than (e.g., less than) an expected TSF value.Alternatively, a processor in such a communication device (e.g.,wireless station (STA)) may operate to determine that the at least oneadditional apparatus has undergone the restart or reset based on arestart count value within the first signal.

For example, a receiver communication device (e.g., STA) may receive acommunication from another communication device (e.g., AP). Then, basedon analysis of the receiver communication device (e.g., STA) may assumethat the other communication device (e.g., AP) has undergone a restartor reset. In addition, the receiver communication device (e.g., STA) mayalso check if a particular (singular) bit in that communication is setto a particular or predetermined value to indicate that the othercommunication device (e.g., AP) wants the (at least one) receivercommunication device (e.g., STA) to send its respective current TSFvalue to the other communication device (e.g., AP) so that the othercommunication device (e.g., AP) can reset its respective TSF value tothat which is received from the (at least one) receiver communicationdevice (e.g., STA).

For example, 1 bit may be indicated within this communication from theother communication device (e.g., AP) to indicate whether the othercommunication device's (e.g., AP's) TSF is currently synchronized ornot. Some further comments are provided below, in which such anothercommunication device may generally be referred to as an AP, and one ormore receiver communication devices may generally be referred to asSTA(s). In accordance with the currently developing IEEE 802.11ah/TGah,there are non-traffic indication map (TIM) power save (PS) and targetwake time (TWT) STAs scheduled some time into the future. After an APreboots, the AP would be creating a new schedule for STAs, but non-TIMPS and TWT STAs are still operating with the old schedule. Also, such anAP has no idea how to avoid non-TIM PS and TWT STAs using the oldschedule. By recovering the TSF (e.g., such as from a communication fromone of the STAs) and using old schedule information, AP may ten rebuilda new schedule around these STAs. Hence, detecting if AP has restartedmay not necessarily be enough in all circumstances. For example, insteadof 8-bit restart count and for TSF recovery, a 1-bit indication may beused to signal whether AP TSF is currently synchronized or not withother STAs in the BSS.

Such a (singular) bit being set to a predetermined value (e.g., 0 or 1,depending on the desired implementation) indicates AP is currently notTSF-synchronized. If it is not set, then the AP requests the TSF fromone or more of the STAs, the STAs may choose to send its respective TSFto AP, and the STAs do not correct their own respective TSF using theAP's TSF value.

An AP may preserve per-STA association information (e.g., such as usingsecurity keys). As such, an AP may also be implemented to keep the oldschedule information. An AP may be operative such that it prefers not toinform a waking STA to know that it blacked out (e.g., reset orrestarted). Also, it may be preferable that such an AP will not haveinterference from a previous schedule (e.g., AP wants to recover oldschedule and keep using it). As such, an AP may need an old TSF to avoidletting STA know that it blacked out (e.g., the AP needs old TSF tore-use old schedule).

Such an AP may then employ such a bit to request old TSF from a STA thatwakes. Based on this, such an AP may correct the new TSF value to matchthe old TSF value. The waking STA that sees that the bit is set willknow that it does not need to undergo re-association, even though itsees that the AP TSF is different than the STA TSF (e.g., AP TSF<STATSF). Later waking STA(s) will then see the expected TSF and therefore,and correctly recognize that it/they do not need to associate again.Also, a STA that sees the bit set will not its respective local TSF.

In the situation that an AP loses per-STA association information, theneach respective STA wakes operates knowing that it needs to initiate anassociation. For example, each STA examines TSF and sees that the AP TSFis different than the STA TSF (e.g., AP TSF<STA TSF). In someembodiments, if AP TSF<STA TSF and bit is not set, then the STAinitiates association. Therefore, AP resets TSF at restart to allow STAto perform this test. In some embodiments, an AP may operate to avoidold wake times, of which it has a record, and this may potentially be atodds with the fact that it has lost all association information. An APcan ask for an old TSF in order to allow an offset correction to knowhow old schedule fits against current TSF values, allowing the AP toavoid overlapping the old schedule with a new one. Such an AP need notadjust restarted TSF when it receives old TSF, and a STA that sees thebit set need not modify its local TSF.

FIG. 14 is a diagram illustrating an embodiment of a method foroperating one or more wireless communication devices. Referring tomethod 1400 of FIG. 14, the method 1400 begins by receiving a firstsignal from at least one additional communication device (e.g., byoperating at least one communication interface of the communicationdevice to), as shown in a block 1410.

The method 1400 continues by analyzing the first signal (condition 1) todetermine whether or not the at least one additional communicationdevice has undergone a restart or reset and (condition 2) to determinewhether or not the first signal includes a request for a timingsynchronization function (TSF) value from the communication device, asshown in a block 1420. If both of these conditions 1 and 2 are met(e.g., upon determination that the at least one additional communicationdevice has undergone the restart or reset and upon determination thatthe first signal includes the request for the TSF value from thecommunication device), as shown in a block 1430.

The method 1400 then operates by generating a second signal thatincludes the TSF value from the communication device, as shown in ablock 1430. The method 1400 continues by operating at least onecommunication interface of the communication device to transmit a secondsignal to the at least one additional communication device, as shown ina block 1440.

It is also noted that the various operations and functions as describedwith respect to various methods herein may be performed within awireless communication device, such as using a processor, processingcircuitry, baseband processing module and/or a processing moduleimplemented therein, (e.g., such as in accordance with the basebandprocessing module 64 and/or the processing module 50 as described withreference to FIG. 2, the equivalent of which may be implemented asprocessors, processing circuitries, etc.) and/or other componentstherein. For example, such a baseband processing module can generatesuch signals and frames as described herein as well as perform variousoperations and analyses as described herein, or any other operations andfunctions as described herein, etc. or their respective equivalents.

In some embodiments, such a baseband processing module and/or aprocessing module (which may be implemented in the same device orseparate devices) can perform such processing to generate signals fortransmission using at least one of any number of radios and at least oneof any number of antennae to another wireless communication device(e.g., which also may include at least one of any number of radios andat least one of any number of antennae) in accordance with variousaspects of the invention, and/or any other operations and functions asdescribed herein, etc. or their respective equivalents. In someembodiments, such processing is performed cooperatively by a processingmodule in a first device, and a baseband processing module within asecond device. In other embodiments, such processing is performed whollyby a baseband processing module or a processing module.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “operably coupled to”, “coupled to”, and/or “coupling” includesdirect coupling between items and/or indirect coupling between items viaan intervening item (e.g., an item includes, but is not limited to, acomponent, an element, a circuit, and/or a module) where, for indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.As may even further be used herein, the term “operable to” or “operablycoupled to” indicates that an item includes one or more of powerconnections, input(s), output(s), etc., to perform, when activated, oneor more its corresponding functions and may further include inferredcoupling to one or more other items. As may still further be usedherein, the term “associated with”, includes direct and/or indirectcoupling of separate items and/or one item being embedded within anotheritem. As may be used herein, the term “compares favorably”, indicatesthat a comparison between two or more items, signals, etc., provides adesired relationship. For example, when the desired relationship is thatsignal 1 has a greater magnitude than signal 2, a favorable comparisonmay be achieved when the magnitude of signal 1 is greater than that ofsignal 2 or when the magnitude of signal 2 is less than that of signal1.

As may also be used herein, the terms “processing module”, “module”,“processing circuit”, and/or “processing unit” (e.g., including variousmodules and/or circuitries such as may be operative, implemented, and/orfor encoding, for decoding, for baseband processing, etc.) may be asingle processing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may have anassociated memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of the processing module, module, processing circuit, and/orprocessing unit. Such a memory device may be a read-only memory (ROM),random access memory (RAM), volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

The present invention has been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention. Further, theboundaries of these functional building blocks have been arbitrarilydefined for convenience of description. Alternate boundaries could bedefined as long as the certain significant functions are appropriatelyperformed. Similarly, flow diagram blocks may also have been arbitrarilydefined herein to illustrate certain significant functionality. To theextent used, the flow diagram block boundaries and sequence could havebeen defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claimed invention. One of average skill in the artwill also recognize that the functional building blocks, and otherillustrative blocks, modules and components herein, can be implementedas illustrated or by discrete components, application specificintegrated circuits, processors executing appropriate software and thelike or any combination thereof.

The present invention may have also been described, at least in part, interms of one or more embodiments. An embodiment of the present inventionis used herein to illustrate the present invention, an aspect thereof, afeature thereof, a concept thereof, and/or an example thereof. Aphysical embodiment of an apparatus, an article of manufacture, amachine, and/or of a process that embodies the present invention mayinclude one or more of the aspects, features, concepts, examples, etc.described with reference to one or more of the embodiments discussedherein. Further, from figure to figure, the embodiments may incorporatethe same or similarly named functions, steps, modules, etc. that may usethe same or different reference numbers and, as such, the functions,steps, modules, etc. may be the same or similar functions, steps,modules, etc. or different ones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of the various embodimentsof the present invention. A module includes a functional block that isimplemented via hardware to perform one or module functions such as theprocessing of one or more input signals to produce one or more outputsignals. The hardware that implements the module may itself operate inconjunction software, and/or firmware. As used herein, a module maycontain one or more sub-modules that themselves are modules.

While particular combinations of various functions and features of thepresent invention have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent invention is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. An apparatus comprising: at least onecommunication interface configured to receive a first signal from anaccess point (AP); and a processor configured to: analyze the firstsignal to determine whether or not the AP has undergone a restart orreset; determine whether or not the first signal includes a request fora timing synchronization function (TSF) value from the apparatus basedon a singular bit within the first signal being set to a predeterminedvalue; and upon determination that the AP has undergone the restart orreset and upon determination that the first signal includes the requestfor the TSF value from the apparatus, generate a second signal thatincludes the TSF value from the apparatus; and wherein: the at least onecommunication interface configured to transmit the second signal to theAP; the apparatus being one wireless station (STA) of a plurality ofwireless stations (STAs); before the AP has undergone the restart orreset, the plurality of STAs configured to awaken respectively at afirst plurality of target wake times (TWTs) in accordance with a firstschedule; and after the AP has undergone the restart or reset, theplurality of STAs configured to awaken respectively at a secondplurality of TWTs in accordance with a second schedule.
 2. The apparatusof claim 1, wherein the processor is further configured to: determinethat the AP has undergone the restart or reset when a TSF value withinthe first signal is different than an expected TSF value.
 3. Theapparatus of claim 1, wherein the processor is further configured to:determine that the AP has undergone the restart or reset based on arestart count value within the first signal.
 4. The apparatus of claim1, wherein the AP is further configured to: generate the second schedulebased on a time reference that is based on the TSF value received fromthe apparatus.
 5. The apparatus of claim 1, wherein the AP is furtherconfigured to: reset or adjust a local TSF value therein based on theTSF value included within the second signal from the apparatus.
 6. Anapparatus comprising: at least one communication interface configured toreceive a first signal from at least one additional apparatus; and aprocessor to: analyze the first signal to determine whether or not theat least one additional apparatus has undergone a restart or reset andto determine whether or not the first signal includes a request for atiming synchronization function (TSF) value from the apparatus; and upondetermination that the at least one additional apparatus has undergonethe restart or reset and upon determination that the first signalincludes the request for the TSF value from the apparatus, generate asecond signal that includes the TSF value from the apparatus; and the atleast one communication interface configured to transmit the secondsignal to the at least one additional apparatus.
 7. The apparatus ofclaim 6, wherein the processor is further configured to: determine thatthe at least one additional apparatus has undergone the restart or resetwhen a TSF value within the first signal is different than an expectedTSF value.
 8. The apparatus of claim 6, wherein the processor is furtherconfigured to: determine that the at least one additional apparatus hasundergone the restart or reset based on a restart count value within thefirst signal.
 9. The apparatus of claim 6, wherein the processor isfurther configured to: determine that the first signal includes therequest for the TSF value from the apparatus based on a singular bitwithin the first signal being set to a predetermined value.
 10. Theapparatus of claim 6, wherein: the apparatus being one wireless station(STA) of a plurality of wireless stations (STAs); before the at leastone additional apparatus has undergone the restart or reset, theplurality of STAs configured to awaken respectively at a first pluralityof target wake times (TWTs) in accordance with a first schedule; andafter the at least one additional apparatus has undergone the restart orreset, the plurality of STAs configured to awaken respectively at asecond plurality of TWTs in accordance with a second schedule.
 11. Theapparatus of claim 10 further comprising: the at least one additionalapparatus configured to generate the second schedule based on a timereference that is based on the TSF value received from the apparatus.12. The apparatus of claim 6 further comprising: the at least oneadditional apparatus configured to reset or adjust a local TSF valuetherein based on the TSF value included within the second signal fromthe apparatus.
 13. The apparatus of claim 6, wherein: a wireless station(STA), wherein the at least one additional apparatus being an accesspoint (AP).
 14. A method for execution by a communication device, themethod comprising: operating at least one communication interface of thecommunication device to receive a first signal from at least oneadditional communication device; analyzing the first signal to determinewhether or not the at least one additional communication device hasundergone a restart or reset and to determine whether or not the firstsignal includes a request for a timing synchronization function (TSF)value from the communication device; and upon determination that the atleast one additional communication device has undergone the restart orreset and upon determination that the first signal includes the requestfor the TSF value from the communication device: generating a secondsignal that includes the TSF value from the communication device; andoperating at least one communication interface of the communicationdevice to transmit the second signal to the at least one additionalcommunication device.
 15. The method of claim 14 further comprising:determining that the at least one additional communication device hasundergone the restart or reset when a TSF value within the first signalis different than an expected TSF value.
 16. The method of claim 14further comprising: determining that the at least one additionalcommunication device has undergone the restart or reset based on arestart count value within the first signal.
 17. The method of claim 14further comprising: determining that the first signal includes therequest for the TSF value from the communication device based on asingular bit within the first signal being set to a predetermined value.18. The method of claim 14, wherein: the communication device being onewireless station (STA) of a plurality of wireless stations (STAs); andfurther comprising: before the at least one additional communicationdevice has undergone the restart or reset, the plurality of STAsoperating by awakening respectively at a first plurality of target waketimes (TWTs) in accordance with a first schedule; and after the at leastone additional communication device has undergone the restart or reset,the plurality of STAs operating by awakening respectively at a secondplurality of TWTs in accordance with a second schedule.
 19. The methodof claim 14 further comprising: the at least one additionalcommunication device operating by resetting or adjusting a local TSFvalue therein based on the TSF value included within the second signalfrom the communication device.
 20. The method of claim 14, wherein thecommunication device being a wireless station (STA), and the at leastone additional communication device being an access point (AP).